1. Field of the Invention
The present invention relates to electronic musical instruments, and more particularly to a system for providing reiteration of percussion sounds in an electronic organ.
2. Prior Art
Electronic musical instruments, such as electronic organs, often include a system for automatically reiterating a sound corresponding to a note so long as the keyswitch for that note is depressed to produce percussion effects such as the sound of a xylophone or a marimba. The usual way of producing reiteration of a percussion note is to apply a DC voltage produced by depression of a keyswitch as one input to an AND gate, and to apply as the other input to the AND gate a reiterating signal, such as a signal of rectangular waveform having a frequency corresponding to the desired reiteration rate (e.g., five times a second), and utilizing the output of the AND gate to control an audio gate, which is operative to connect a signal from a tone generator to a filtering and amplifying means. Thus, as the key is held, the reiteration signal goes "on" and "off", alternately closing and opening the audio gate, causing the played note to reiterate at a predetermined rate.
In prior art systems of this kind of which applicant is aware, the duty cycle of the reiterating signal is fifty percent or less; that is, it is at its positive level half of the time or less and "off" for half of the time or longer. While the reiterating signal is always present as one input to the AND gate, because it is ineffective half or more of the time to open the AND gate, if one plays the keys of the organ rapidly there is a good chance that the reiterating signal will be at its "off" condition at the instant a key is played, and no sound will be produced. This is very disconcerting to the organist who when playing at his own tempo plays a key and no sound is produced. One proposed solution for this problem is to provide in the reiteration system a circuit that produces an enabling reiteration pulse any time any keyboard key is actuated, thereby assuring production of a sound in response to the initial depression of the key. However, with this arrangement, if any key is being held at the time an additional key or keys are played, all of the actuated keys will strike at the same time, causing a strange and generally objectionable percussion sound.